Optimizing the performance of iron coke by coal blending: Insights from the metallurgical properties and structural characteristics

Abstract

Listen

Translate article

Iron coke has gained widespread attention for its advantages in carbon reduction and efficient resource utilization. However, the structure and strength of iron coke have constrained its further advancement. This study systematically explores the impact of different coal blending structures on the three-dimensional structure and tensile strength of iron coke through three-dimensional reconstruction technology. It highlights the improvement mechanism of 1/3 coking coal addition on the microstructure and metallurgical properties of iron coke. The study shows that the tensile strength of iron coke increases with the addition of coking coal, while lean coal exhibits the opposite trend. The addition of an appropriate proportion of 1/3 coking coal (20–22 %) enhances the tensile strength and mechanical strength of iron coke, reaching the level of second-grade coke. However, an addition exceeding 22 % leads to increased porosity and reduced strength due to the high volatile content. Finite element analysis demonstrates that stress is primarily localized in regions with thinner pore walls and at the iron-carbon interface, and the aggregation effect of iron particles further causes stress concentration. Iron coke reactivity initially diminishes and subsequently rises with the addition of 1/3 coking coal, and it shows a linear negative correlation with the strength after reaction. Structural evolution reveals that the addition of 1/3 coking coal reduces the orderliness of carbon microcrystals, thereby increasing the active sites for gasification reactions. Meanwhile, the initial reduction followed by an increase in the specific surface area of iron coke can impact adsorption sites, thereby influencing reaction activity. These findings not only provide a new understanding of the structure-performance relationship of iron coke but also offer practical guidance for iron coke production.